IN VITRO CULTURE OF RED MAPLE STEM SEGMENTS

The red maple (Acer rubrum L.), one of the sugar-producing maple species is native to North America. The species has been introduced into China in recent years, but the quantity of introduced trees is too small to meet the needs of normal experiments for the study of its introduction and acclimatization. That is why we have been engaging in the culture of stem segments in vitro.Stem segments, 1-1.5 cm in length, were surface-sterilized in 70% alcohol and in 0.10% HgCl₂ water solution and cultured on newly formulated agar-sugar basal medium supplemented with NAA 2mg/l, ZE 2mg/l and GA 5mg/l. The culture was conducted under controlled temperature (25±3℃) and light (1,000-2,000 lux, 12 hours a day) in the culture room. On the 15th day of the culture, white calluses formed on the stem nodes. When the calluses were subcultured on the basal medium supplemented with NAA 0.5 mg/l, KT 2 mg/l, ZE 2 mg/l, and GA 3 mg/l for 20 days, they developed into dark green spheriods or ovoids. In another 20 days 20% of these sphriods and ovoids produced ab- normal shoots. When the shoots were transferred to the basal medium modified by addition of IBA 0.1 mg/l, BA 2 mg/l, ZE 0.5 mg/l and GA 0.3 mg/l, the normal shoot growth occurred satisfactorily. Another way for successful shoot induction and growth was to transfer the calluses straight to this medium for subclture. shoots sprouted from the lower part of the calluses near the medium surface. Roots were induced successfully in the basal medium supplemented with IBA 0.5 mg/l. The rooted plantlets began their normal growth two weeks after being transplanted in the culture soil (pH 6).